Either alloy can be used with O/A or TIG. Use flux with O/A, no flux for TIG. Which one to use depends on what metal you are welding or brazing. For brazing steel the most common alloy used is "low-fuming bronze", actually a low-zinc brass.

John

 

The phosphorus is added to copper to braze clean copper with o/a fluxless. I would not use it with TIG.

 

There seems to be some confusion here between phosphor bronze and "phosphor copper", both of which are made as welding / brazing rods. Phosphor bronze is a standard tin bronze with a fraction of a per cent phosphorus as a deoxidizer. It can be used with TIG or O/A and is also made as MIG wire and as stick electrodes.

Phosphor copper is copper with a large amount (5 - 7%) of phosphorus. It is kind of like sil-phos without the silver and is used where sil-phos is used (brazing copper refrigeration lines, etc.) as a lower-cost alternative.

Confusing the two is quite common- I recently got phosphor copper from my LWS instead of phosphor bronze and didn't notice until I started welding!

John

 

OK, so they are good for different things. But what are those things?

If I want to braze weld copper pipe to a sheet of copper?
Repair cast iron?
Braze weld a piece of mild steel to cast iron?
Braze a steel nut onto a piece of threaded rod also steel?
Braze weld a piece of thin galvanized sheet metal to something else that is galvanized?
Braze together two thin pieces of stainless tubing?
Braze over something welded in mild steel for good appearences?

 

OK, so they are good for different things. But what are those things?

>If I want to braze weld copper pipe to a sheet of copper?
I'd use sil-phos 5% (copper/phosphorus/silver) or 0% (no silver) for a better color match. Flux is not necessary if it is clean to start with.
O/A is fastest, but air/acetylene works too.

>Repair cast iron?
O/A silicon bronze WITH flux, or nickel-silver (special flux for this higher temperature). Or stick with Ni99 rod.

>Braze weld a piece of mild steel to cast iron?
This depends on the joint configuration. The shrinking steel can cause cracks, but if the shape is right, O/A silicon bronze should work.

> Braze a steel nut onto a piece of threaded rod also steel?
Tough one. I've used silicon bronze for this, but if the allthread is zinc plated, the plating burning off can make it difficult to get a good braze.

>Braze weld a piece of thin galvanized sheet metal to something else that is galvanized?
I wouldn't use O/A on galvanized. You could try a zinc repair "solder", but don't expect strong results.

>Braze together two thin pieces of stainless tubing?
High silver content rod is supposed to work with special flux. I've never had luck with it, but since I have TIG, I haven't bothered to try too hard.

>Braze over something welded in mild steel for good appearences?
Whatever sticks and gets the look you're after?

 

Thanks guys for taking the time! Much appreciated! :drinkup:

Another question though, I found a list over the different filler materials that has copper in them.
Leaving aluminum out of it, you've mentioned most of the others except Naval bronze RBCuZn-A. Is that the same as Low Fuming Bronze except for the low fuming part?

• Naval Bronze (RBCuZn-A)
• Nickel Bronze (RBCuZn-B)
• Low Fuming Bronze (RBCuZn-C)
• Nickel Silver (RBCuZn-D)
• Silicon Bronze (ERCuSi-A)
• Deoxidised Copper (ERCu)
• Phosphor Bronze A (ERCuSn-A)
• Phosphor Bronze C (ERCuSn-C)
• Aluminum Bronze A-1 (ERCuAl-A1)
• Aluminum Bronze A-2 (ERCuAl-A2)
• Aluminum Bronze A-3 (ERCuAl-A3)
• Nickel-Aluminum Bronze (ERCuNiAl)
• Manganese-Nickel-Aluminum (ERCuMnNiAl)

 

The -A material is used if more corrosion resistance is wanted, however its use is very seldom. It is slightly more finicky to work with to resist boiling the material. RBCuZn-B,C,and D are the most commonly used. ERCu is for welding copper.